What’s the one word, the secret of the future? “Plastics,” or so Dustin Hoffman was told in the classic film "The Graduate."

Erik Zettler heard the same word, not as an opportunity whispered in his ear, but as a new hazard in the sea.

The microbial ecologist with the Sea Education Association in Woods Hole spoke Saturday at the Cape Cod Natural History Conference at Cape Cod Community College on the “Plastisphere” in the ocean and why animals are eating it up.

“Classically it’s been about sea turtles and birds,” Zettler said of issues revolving around animals ingesting plastic bags and such. “With albatross chicks as their parents feed them lots of plastic is regurgitated and builds up in (the chicks). It turns out the more you look everywhere you find things that eat plastic, everything from zooplankton to great whales. There was a study that came out a couple of months ago about sperm whales that were opened up and had a lot of plastic in their stomachs. So why are so many things eating plastic?”

It turns out it’s the same reason people eat chocolate. It tastes good.

“Some are indiscriminate feeders (like clams) and some are relatively selective feeders,” Zettler reflected. “A lot of animals use smell and taste so we started thinking perhaps anything that gets into the water gets a microbial biofilm on it that makes it smell and taste like a piece of food.”

Biofilm may not sound like a tasty treat but that depends on your genus or species.

“Some algae such diatoms produce DMS (dimethyl sulfide) which is a feeding cue for seabirds. They hone in on food by DMS and plastic in the ocean produces DMS at levels discernible by seabirds. So some of them try to eat the plastic because it smells like food?” Zettler wondered.

Sea turtles are known to swallow plastic bags because they look like jellyfish but much of the plastic in the sea breaks down into miniscule pieces. Birds and fish detect it because they sense it. So Zettler decided to examine that.

“It was an interesting experiment to do,” he recounted. “We took plastic and put it in the water for different amounts of time and compared the feeding on the pieces.”

The longer it was in the water the more microbial life that attached itself to the plastic surface.

“We started fishing out plastic and looking at the DNA on the plastic and we would put different kinds of plastic in the water and go back and sample it periodically to see what kinds of communities develop and what different kinds of microbes there were. And we wanted to see if the microbes help break the plastic down into smaller pieces and made it heavier so it sinks,” Zettler explained.

Zettler said much of the weighted plastic sinks and thus isn’t sampled or measured in ocean tows so there is more out there than we imagine.

They fished out pieces of plastic that were smaller than a dime, extracted DNA from the surface and sequenced it.

“We found over a thousand different kinds of microbes on a single piece of plastic,” Zettler marveled. “There were bacteria, diatoms, things grazing on them, predators, decomposers, a whole little ecosystem on a piece of plastic. We found potential disease-causing organisms as well that might be a concern to people and aquaculture.”

Most of this plastic comes from the land. Less than 10 percent of plastic waste is recycled. In many countries trash is dumped at sea or nearby.

Small pieces can be filtered out of the water by barnacles, oysters, copepods, but larger animals ingest them as well.

“If tuna don’t eat plastic they eat other fish that eat plastic,” Zettler noted. “It might move up the food chain. If the pieces are big enough they can cause an obstruction and smaller things can act like sponges for toxic chemicals. It’s sure not good for us. Plastic absorbs toxic chemicals; PCBs and such stick to plastic and things eat them. Some chemicals can move into the liver and tissues.”

While the waters of Cape Cod might not have the levels of plastics of seas elsewhere Zettler noted currents flow around the world.

“Ocean water can come from anywhere in the Atlantic,” he said. “So it is a problem that will have to be dealt with globally.”